Fixed position fasteners for disposable absorbent garments

ABSTRACT

A fastener for disposable diapers having a first pair of fastener members (70,72) attached to an outer cover (20) of the disposable diaper, a second pair of fastener members (74,76) attached to the outer cover (20). The fastener members (70,72 and 74,76) have a complementary cross section for mating engagement and are releasably interlockable. Each of the fastener members (70,72,74,76) are sufficiently flexible to prevent skin irritation of a wearer and sufficiently inflexible to prevent unwanted unfastening of the fastener members during normal use. A value (E) (I), the product of the Modulus of Elasticity and the Moment of Inertia is utilized as a measure of the flexibility and inflexibility of the fastener. Each fastener member, for example, fastener member 70 has an essentially flat base portion (90) with an aperture (92) separating a pair of clasps (94,96).

This is a continuation of application Ser. No. 773,742, filed on Sept.6, 1985 and now abandoned.

TECHNICAL FIELD

The present invention relates, generally, to the field of disposablediapers utilized for the absorption and containment of urine and otherbody exudates. More particularly, the present invention relates toform-fitting, self-adjusting disposable diapers with fixed positionfasteners. Most particularly, the present invention relates to fixedposition fasteners for disposable diapers are sufficiently flexible toprevent skin irritation and sufficiently inflexible to prevent unwantedunfastening during normal use.

BACKGROUND ART

Disposable garments are generally well known in the art and have becomean important and an essentially indispensable sanitary protection item,most particularly in the field of infant and child care where disposablediapers provide for the absorption and containment of urine and otherbody exudates. Present commercially available disposable diapers aregenerally unitary, preshaped and prefolded, and comprised of a porousfacing layer, a fluid impervious backing sheet with an absorbentmaterial disposed therebetween. These presently available disposablediapers have met a particular need and have become ever increasinglypopular. However, even though the presently available disposable diapersare efficient and effective they have several drawbacks that have beenidentified by mothers of infants wearing the diapers. These mothers havestrongly voiced their desire to be able to obtain disposable diapersthat are aesthetically neat and attractive when on their infant orchild. The aesthetically neat criteria have been identified as includinga trim, slim fit, and a neat fitting waist and legs that do not allowleakage of urine or feces. It has also been found that mothers do notwant their children to look rumpled, bulky, or messy. In addition, thesemothers have expressed a desire to either have a disposable diaper thatfits more sizes of babies or to have disposable diapers provided in moresizes.

Another drawback identified by these mothers has been the problemassociated with skin irritation caused by urine, feces, or moisturetrapped next to the skin. They have again been very vocal in theirdesire to obtain disposable diapers that avoid or solve this problem.

Another major drawback is associated with the methods provided to securethe diaper around the baby. The method most utilized in presentcommercially available disposable diapers is the plastic sealable tape.Initially, the fastening tapes introduced on disposable diapers were notresealable, which meant that when the mother wished to check the diaperfor wetness or to adjust the fit, the tapes could not be resealed. This,in turn, meant that the diaper, if not ready to be changed, would haveto be thrown away. Presently, disposable diapers use tapes that aremanufactured to be resealable. However, it has been found that the tapespresently used are subject to contamination by baby powder or baby oilor other substances which prevent them from resealing, or in the worstcase, prevent them from sealing upon initial use. The mothers indicatethat they want disposable diapers that have fasteners that are notsubject to contamination, that are always resealable and that are noteasily unfastenable by babies. The attempt to provide tapes that arealways resealable has caused some manufacturers to utilize strongeradhesives on the tapes. Unfortunately, however, the stronger adhesiveshave a tendency to tear the outer cover which may also cause the diaperto be unusable.

Furthermore, the fastening tapes used on the present disposable diapercan also have a detrimental effect upon fit. Because the tapes are madeto be sealable on any portion of the outer cover, and there is noindication to mothers where the tapes should be sealed, the tapes arevery often sealed to the outer cover at the wrong position which hasseveral detrimental effects. First, the diaper does not fit on the babyproperly, for example, if too loose, the diaper falls down or droops atthe waist, or if too tight, causes strain in the outer cover which canmake the baby uncomfortable. Second, the improper positioning of thetapes can cause the leg openings to gap thus causing leakage. Third, inan attempt to reposition the tapes to correct the above problems mothershave found that there is an increased potential to contaminate the tapesthus causing the disposable diaper to be unusable.

The present application teaches an improved disposable diaper which isanatomically form-fitting and anatomically self-adjusting to provide anattractively slim, trim diaper for the baby to wear. The diaper providedby the present invention is trim, does not gap at the legs or waist, andhas virtually contamination-proof refastenable fixed position fasteners.Furthermore, the disposable diaper as provided by the present inventionis breathable and at the same time highly resistant to leakage.

DISCLOSURE OF THE INVENTION

It has now been determined in accordance with the present invention thatan anatomically form-fitting generally self-adjusting disposable diapercan be produced. Advantageously, the disposable diaper of the presentinvention achieves a considerably improved fit and an attractiveappearance when worn by a baby. Furthermore, the components of thedisposable diaper of the present invention are constructed in a novelway from novel materials such that the disposable diaper is snug andcomfortable and does not irritate the skin of the baby. The outer coverof the disposable diaper of the present invention is not onlybreathable, but is resiliently stretchable, thus providing both thebenefits of dry skin and a form-fitting, anatomically self-adjustingdisposable diaper that conforms to the baby's shape. The stretchableouter cover utilized in the disposable diaper of the present inventioncovers and protects the body in all desired places, provides a gentle,but secure, closure at the waist and legs and resists deformation anddegradation during use. Further advantageously, fixed position fastenersprovide a solution to many of the problems encountered with theresealable tapes as used in the prior art. The fasteners, in one aspectof the present invention, have multiple refastenability capabilities,are virtually insensitive to contamination, can provide closure from thewaist opening to each leg opening, can maintain the distance between thewaist opening and each leg opening during use which prevents the waistfrom sagging and the leg openings from gapping, are flexible so thatthey do not restrict the baby's motion and since they are fixed positionpoint-to-point fasteners, in a most preferred embodiment, they arevirtually impossible to fasten incorrectly.

The foregoing, and other advantages of the present invention, arerealized in an anatomically form-fitting, generally self-adjustingdisposable diaper comprising an outer cover, an absorbent structuredisposed within the outer cover, and fixed position, point-to-pointfasteners to secure the diaper around the body of the wearer. The outercover is resiliently stretchable in at least one direction, in oneaspect of the present invention the outer cover is resilientlystretchable in a cross body direction. The outer cover is resilientlystretchable in a range from about 20% to 200%.

The fixed position fasteners comprise a first pair of members attachedto or integral with the back waist section of the outer cover and asecond pair of members attached to or integral with the front waistsection of the disposable diaper. Each of the first pair of fastenermembers have a complementary cross section for mating engagement withthe second pair of members and are releasably interlockable with each ofthe second pair of fastener members. Each of the fastener members aresufficiently flexible to prevent skin irritation of a wearer of thedisposable diaper while at the same time sufficiently inflexible toprevent unwanted unfastening during normal use. A measure of theflexibility and inflexibility of the fastener members is the value(E)(I), the product of the Modulus of Elasticity (E) and the Moment ofInertia (I) calculated from the formula EI=L³ M/48. The fastener membersattached to the back waist section of the outer cover may be attached insuch a way that the back waist section overlaps the front waist sectionwhen the fasteners are interlocked around the waist of the baby.Alternatively, the fastener members may be attached to or integral withthe back waist section and front waist section whereby the back waistsection is overlapped by the front waist section.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1A is a side view of the disposable diaper of the invention shownsecured around a baby;

FIG. 1B is a front view of the disposable diaper of the presentinvention shown secured around a baby;

FIG. 1C is a back view of the disposable diaper of the present inventionshown secured around a baby;

FIG. 1D is a front view of the disposable diaper of the presentinvention showing the disposition of the diaper on the baby after beingworn for a period of time;

FIG. 2 is a plan view of an embodiment of the disposable diaper of thepresent invention shown in a semi-finished condition;

FIG. 3 is a sectional view of cross section 3--3 shown in FIG. 2;

FIG. 4 is a plan view of the disposable diaper shown in FIG. 2 in afinished condition, but without fasteners;

FIG. 5 is a sectional view of cross section 5--5 of FIG. 4;

FIG. 6 is a plan view of an alternative embodiment of the disposablediaper of the present invention shown in a semi-finished condition;

FIG. 7 is a sectional view of cross section 7--7 shown in FIG. 6;

FIG. 8 is the alternative embodiment shown in FIG. 6 in a finishedcondition;

FIG. 9 is a sectional view of cross section 9--9 as shown in FIG. 8;

FIG. 10 is a plan view of a further alternative embodiment of thedisposable diaper of the present invention;

FIG. 10A is a sectional view of cross section 10A--10A as shown in FIG.10;

FIG. 11 is a plan view of a still further alternative embodiment of thedisposable diaper of the present invention;

FIG. 12 is a sectional view of cross section 12--12 as shown in FIG. 11;

FIG. 13 is still another alternative embodiment of the disposable diaperof the present invention;

FIG. 13A is a sectional view of cross section 13A--13A as shown in FIG.13;

FIG. 14 is a plan view of an embodiment of the disposable diaper of thepresent invention showing a first method of attaching fixed positionfasteners to the diaper;

FIG. 15 is a sectional view of cross section 15--15 as shown in FIG. 14;

FIG. 16 is a sectional view of cross section 16--16 as shown in FIG. 14;

FIG. 17 is a perspective view of an embodiment of the disposable diaperof the present invention as it would be secured around a wearer;

FIG. 18 is a sectional view of cross section 18--18 as shown in FIG. 17;

FIG. 19 is a plan view of the disposable diaper of the present inventionshowing a second method of attaching the fixed position fasteners to thediaper;

FIG. 20 is a sectional view of cross section 20--20 as shown in FIG. 19;

FIG. 21 is a sectional view of cross section 21--21 as shown in FIG. 19;

FIG. 22 is a perspective view of an embodiment of the disposable diaperof the present invention as it would be secured around a wearer;

FIG. 23 is a sectional view of cross section 23--23 as shown in FIG. 22;

FIG. 24 is a perspective view of one member of the fixed positionfastener;

FIG. 25 is a perspective view of a second member of the fixed positionfastener; and

FIG. 26 is a perspective view of the two members of the fixed positionfastener shown in an interlocked position.

MODES FOR CARRYING OUT THE INVENTION

The present invention relates, generally, to disposable diapers for theabsorption and containment of urine and other body exudates. The presentinvention relates more especially to disposable diapers that areanatomically form-fitting, generally self-adjusting to achieve anaesthetically pleasing fit on the body of a wearer. Most particularly,the present invention provides fixed position fasteners attached to anouter cover for securing the disposable diaper around a wearer.Accordingly, the present invention will now be described with referenceto certain modes for carrying out the invention within theaforementioned context. Those skilled in the art will realize that sucha description is meant to be exemplary only and should not be deemedlimitative respecting the scope of the present invention, for example,in terms of its construction.

Turning to the figures, in each of which like parts are identified withlike reference characters, FIGS. 1A through 1D show the disposablediaper 10 as it would be worn by a baby. Indicated at 12 and 14 thewaist and leg openings are hemmed. FIGS. 1A, 1B, and 1D indicategenerally at 16 the position of the fasteners. FIG. 1D illustrates theminimal extent the diaper moves from an initial position as indicated bythe dashed lines 18 after being worn by an infant for a period of time.

Turning now to FIG. 2, there is shown an embodiment of the disposablediaper provided by the present invention. An outer cover 20 is shown inplan view with an absorbent structure 22 disposed thereon. Outer cover20 is shown with leg hems 24, back waist flap 26 and front waist flap 28unfolded. Foldline 30 indicates where back waist flap 26 is folded.Similarly, foldline 32 indicates where front waist flap 28 is folded.Foldlines 34 indicate where hems 24 are folded. Line 36 shows theperiphery of absorbent composite 38. Referring to FIG. 3 in conjunctionwith FIG. 2, absorbent structure 22 comprises a liquid permeablebodyside liner 42 bonded to a liquid impermeable barrier 44 withabsorbent composite 38 disposed therebetween. It is contemplated thatany appropriate means for bonding bodyside liner 42 to barrier 44 may beused. A preferable method of bonding bodyside liner 42 to barrier 44 isany autogenous bonds such as the bonds produced by sonic or ultrasonicenergy. A function of the bonding between bodyside liner 42 and barrier44 is to maintain absorbent composite 38 disposed therebetween and tomaintain absorbent structure 22 as a unitary structure. Depending uponthe composition of absorbent composite 38 the bonding between bodysideliner 42 and barrier 44 may be continuous or a series of discretepoints. It is noted that for the sake of clarity only a few autogenousbonding points 40 are shown and numbered. Other methods, such aspressure or heat sensitive adhesives may be used and are to beconsidered within the scope of the present invention. As shown in FIG.3, absorbent structure 22 is disposed upon outer cover 20. The materialsmaking up each component will be discussed in conjunction with laterfigures.

Illustrated in FIG. 4 is the embodiment of the disposable diaper shownin FIG. 2 with waist flaps 26 and 28 folded over absorbent structure 22forming pockets 29 and 31. FIG. 4 also shows hems 24 folded and bonded.Again, any method of bonding may be used, however, autogenous bonding isa preferable method and a series of discrete bonds are represented bynumeral 46. Also indicated are autogenous bonds at 48 which bond theflaps 26 and 28 to the outer cover. As can be appreciated, the foldingof the flaps 26 and 28 over the ends of absorbent structure 22 maintainsabsorbent structure 22 in position in relation to outer cover 20 withoutinhibiting the stretchability of outer cover 20. FIG. 5 is a sectionalview of cross section 5--5 of FIG. 4 and shows the relationship of waistflap 26 when folded over absorbent structure 22. It is to be especiallynoted that there are no direct bonds holding the ends of absorbentstructure 22 to either the outer cover 20 or to waist flaps 26 or 28.This ensures that the stretchability of outer cover 20 is uninhibited byabsorbent structure 22. In addition to front and back waist flaps 26 and28 there are autogenous bonds, indicated at 50, bonding absorbentstructure 22 to outer cover 20 in the crotch section of the diaper.Although these bonds may inhibit the stretchability of the crotchsection of outer cover 20, the bonds do not inhibit the functionality ofouter cover 20 since there is minimal need for outer cover 20 to bestretched in a cross body direction in the crotch area.

FIGS. 6-9 illustrate an alternative embodiment of the disposable diaperof the present invention. Referring to FIGS. 6-9 together, it is seenthat absorbent structure 22 comprises a bodyside liner 42, a liquidimpermeable barrier 44 with an absorbent composite 38 disposedtherebetween. As shown in FIG. 7, which is a sectional view of crosssection 7--7 of FIG. 6, the bodyside liner 42 is bonded to outer cover20 rather than to barrier 44 as disclosed in the previous embodiment. Inorder to maintain the shape of absorbent composite 38 during manufacturethe absorbent composite may be wrapped with tissue or have a tissue 43bonded to barrier 44 as shown in FIGS. 7 and 9. The bodyside liner 42 isbonded to outer cover 20 when outer cover 20 is in a stretchedcondition. Bodyside liner 42 may be bonded to outer cover 20 by anyconventional method with the preferable method being autogenous bondingas discussed hereinabove and indicated generally at 45. FIGS. 8 and 9show the disposable diaper shown in FIGS. 6 and 7 when outer cover 20 isin an unstretched condition. It is noted that the figures are not meantto be dimensionally accurate. Referring especially to FIG. 9, which is asectional view of cross section 9--9 in FIG. 8, it can be seen that whenouter cover 20 is relaxed, after bodyside liner 42 is bonded to it,bodyside liner 42 is drawn under absorbent structure 22 by outer cover20, and as can be appreciated, this method does not inhibit thestretchability of outer cover 20. The disposable diaper illustrated inFIGS. 6 through 9 has a relatively narrow hem 52 at the back waistsection and a relatively narrow hem 54 at the front waist section ratherthan the wider hems made by waist flaps 26 and 28 illustrated in FIGS. 2through 5.

FIG. 10 illustrates a further alternative embodiment of the disposablediaper of the present invention in which elastic members 56 are showndisposed within the crotch section of absorbent structure 22. Elasticmembers 56 are adhesively bonded to either bodyside liner 42 or tobarrier 44. It is preferable that elastic members 56 are bonded tobodyside liner 42 because absorbent structure 22 is caused to form acupped shape by the tension of elastic members 56 when the diaper isplaced on an infant. Autogenous bonds 40 which bond bodyside liner 42 tobarrier 44 are shown only partially in FIG. 10 as are autogenous bonds48. It is noted that autogenous bonds 50 which bond absorbent structure22 to outer cover 20 are shown inside elastic member 56. Alsoillustrated in FIGS. 10 and 10A are waist tucks 57 on the outermostsections of back waist flap 26 and front waist flap 28. The waist tucks57 cause the waist to appear straight across when the diaper is securedaround a baby and provide a smooth contour near the fastener position.The waist tucks 57 are situated near the extreme edges of front and backwaist flaps 26 and 28, respectively, to be folded over as shown moreclearly in FIG. 10A, which is a sectional view of cross section 10A--10Aas shown in FIG. 10. The distance represented at 59 is the range of from1/4 inch to 1/2 inch and the fold distance, represented at 61 isapproximately 1/4 inch. In addition to causing the waist to appearstraight across the baby, the waist tucks 57 cause the waist to staycloser to the baby thereby eliminating any tendency for the waist togap. Without the gapping the appearance of the diaper on the baby isimproved and the waist area fits more snugly without adding unduetension to the waist area. The waist tucks are preferably held in placeby autogenous bonds indicated at 63. As discussed hereinabove, otherbonding methods may be utilized and are to be considered within thescope of the present invention.

FIGS. 11 and 12 illustrate a still further embodiment of the disposablediaper of the present invention wherein an elastic member 58 is disposedwithin back waist flap 26 and an elastic member 60 is disposed withinfront waist flap 28. Also, elastic members shown at 62 are disposed inleg hems 24. FIG. 12 is a sectional view of cross section 12--12 shownin FIG. 11 and shows the disposition of elastic members 56 and 62 in theabsorbent structure 22 and leg hems 24 respectively. As indicatedearlier, autogenous bonds 50 bond liquid impermeable barrier 44 to outercover 20 while autogenous bonds 40 bond liquid permeable layer 42 toliquid impermeable layer 44 of the absorbent structure with absorbentcomposite 38 disposed therebetween. Also shown in FIG. 12 are autogenousbonds 46 bonding hems 24 to outer cover 20 with elastic members 62disposed within hems 24. It is noted that hems 24 are made up ofportions of outer cover 20.

FIGS. 13 and 13A show the disposable diaper shown in FIGS. 6 through 9with elastic member 58 disposed in hem 52, elastic member 60 disposed inhem 54 and elastic members 62 disposed in leg hems 24. FIG. 13A which isa sectional view of cross section 13A--13A as shown in FIG. 13illustrates waist tucks 65 similar to the waist tucks 57 described inthe discussion relating to FIGS. 10 and 10A. The tucks 65 shown in FIGS.13 and 13A are shown folded and including the elastic member 58. Thisserves to anchor the elastic member 58. Further discussion concerningthe anchoring of elastic members will be presented relating to FIG. 19.

FIGS. 14 through 16 illustrate an embodiment of fixed point fastenersattached to outer cover 20. Outer cover 20 is generally made up of aback waist section 64, a front waist section 66 and a crotch section 68disposed therebetween. Attached to outermost portions of backwaistsection 64 are a pair of fastener members 70 and 72 which will bediscussed in more detail in conjunction with a later figure. Attached tooutermost portions of front waist section 66 are a pair of fastenermembers 74 and 76 which will also be discussed in more detail inconjunction with a later figure. It is noted that fastener members 70and 72 are attached to the inner side of outer cover 20 while fastenermembers 74 and 76 are attached to the outer side of outer cover 20. Itis further noted that fastener members 70 and 72 could be fastened tothe outer side of outer cover 20 and fastener member 74 and 76 could beattached to the inner side of outer cover 20. FIG. 14 shows the fastenermembers 70, 72, 74 and 76 attached to outer cover 20 with autogenousbonds represented at 78. FIG. 15 is a sectional view of cross section15--15 shown in FIG. 14 and shows fastener member 72 attached to outercover 20 with autogenous bonds 78 (shown partially). It should beappreciated that other methods of bonding fastener member 72 to outercover 20 are comprehended and the illustration of autogenous bonds isnot meant to be limiting. FIG. 16 is a sectional view of cross section16--16 of FIG. 14 and shows fastener member 76 bonded to outer cover 20by autogenous bonds 78. Similarly it is noted that other methods ofbonding fastener member 76 to outer cover 20 could be utilized. FIGS. 14through 16 illustrate a method wherein when the pair of fasteners 70 and72 are interlocked with the pair of fasteners 74 and 76, the outermostportions of back waist section 64 overlap front waist section 66. Thisoverlapping fastening method will be seen more clearly in relation toFIGS. 17 and 18.

Referring now to FIGS. 17 and 18, FIG. 17 illustrates a diaper as itwould be secured around a baby with one fastener open to illustrate itsrelative position. FIG. 18 is a sectional view of cross section 18--18of FIG. 17 and shows fastener members 70 and 74 inter1ocked withfastener member 70 bonded with autogenous bonds represented at 78 toouter cover 20 and fastener member 74 attached to outer cover 20 withautogenous bonds 78. It is noted that a first portion of outer cover 20indicated at 77 overlaps a second portion of outer cover 20, indicatedat 79.

Referring now to FIGS. 19, 20, and 21 there is illustrated anotherembodiment of the disposable diaper of the present invention. In thisembodiment, outer cover extension members 80 and 82 are attached tooutermost portions of front waist section 66. Fastener members 74 and 76are attached to extension members 80 and 82. As above, the methods ofattaching extension members 80 and 82 to outermost portions of frontwaist section 66 of outer cover 20 and the fastener members 74 and 76 tothe extension members 80 and 82 can be of several known methods in theart including adhesives, stapling, riveting, sewing, etc. Shown in thisembodiment is autogenous bonding illustrated graphically by dots 78relating to the attachment of the fastener members 70, 72, 74, 76 to theextension members 80, 82 and the attachment of the extension members 80,82 to the outer cover 20.

Also shown in FIGS. 19, 20 and 21 is the aspect of imparting elasticityto the waist sections and leg hems. One method of imparting elasticityis by utilizing elastic members 58 and 60 in the waist sections andelastic members 62 in the leg hems 24. It should be understood that theelastic members 58, 60, 62 may be utilized in any of the embodiments ofthe present invention, but have been shown in only selected figures forthe sake of clarity. The elastic members may comprise any of the usualelastics utilized in the diaper making art such as a thin ribbon ofnatural rubber, etc. A preferred method of imparting elasticity to thewaist sections and/or the leg hems is by extruding a hot meltpressure-sensitive elastomeric adhesive such as that marketed by H. B.Fuller Co. of St. Paul Minn., U.S.A. under the trademark FULLASTIC. Itis to that in FIG. 19 the waist elastic members are shown anchored ateach end by respective fastener members. For example, elastic member 58is anchored at each end by fastener members 70 and 72. In addition, asdiscussed above in relation to FIG. 13 elastic members in the waist maybe anchored by tucks 65. Similarly, elastic member 60 is anchored ateach end by fastener members 74 and 76. Both leg elastic members 62 arealso anchored by the respective fastener members. The anchoring of theelastic members provides for a more even distribution of force therebyprecluding destructive or unattractive tensioning of any one portion ofthe diaper. This aids in the prevention of gapping thereby aiding ineliminating the leakage of urine and feces.

FIG. 22 illustrates the embodiment shown in FIGS. 19-21 as it wouldappear on a child with one fastener open to show the relationship of thefastener members. FIG. 23 is a sectional view of cross section 23--23 ofFIG. 22. FIG. 23 illustrates graphically the butt splice at 88 thatresults from the addition of extension members 80, 82. Note at 88 thatthe two portions of outer cover 20 meet without overlapping.

FIGS. 24 and 25 illustrate an embodiment of the fixed position fastenermembers 70 and 74 respectively. It is anticipated that fastener members70,74 can be manufactured by several methods. One method to efficientlyproduce fastener members 70,74 is to design the members so that they canbe extruded in a substantial length whereby individual members can becut from the substantial length of material. The substantial length canbe rolled and stored for subsequent processing. A further aspect ofefficient production is to design the fastener members to have the samecross section so that each fastener member can be cut from the same rollof material.

It has been determined that the fastener members 70,74 must be carefullydesigned and made from a carefully selected material so that they do notcause the baby's skin to be chafed or irritated and at the same time donot come unfastened easily. Another factor that must be considered inthe selection of the material for fastener members 70,74 is the methodof attachment to the garment or the method by which the fastener members70,74 are to be integrated with the garment. For example, if autogenousbonding is to be utilized, it would be necessary to select a materialthat is autogenously bondable.

A selection criterion for the selection of a material and design forfastener members 70,74 is to consider the Moment of Inertia (I) of thematerial in conjunction with the Modulus of Elasticity (E). Thisselection criterion which involves the product of (E)(I) is utilized asfollows. The value (E)(I) is determined in a material/designcombination, that is, the value (E)(I) is determined for a particulardesign utilizing a particular material. The value (E)(I) is calculatedfrom the following formula taken from the textbook "MechanicalEngineering Design," 2nd Ed. by Joseph E. Shigley, published byMcGraw-Hil, 1972, page 699: ps

    EI=L.sup.3 M/48

wherein M is obtained from ASTM test D-790; and wherein L is defined byASTM test D-790.

It has been determined, for example, for fastener members such asfastener members 70,74 that a material/design combination (E)(I) in therange of about 0.5 pound-inches² to about 3.5 pound-inches² ispreferable in that the fastener members 70,74 when mated or connected donot chafe or irritate the skin of the wearer under normal usage andnormal conditions and do not easily come unfastened under normal usageand normal conditions. A particularly preferable range of values of(E)(I) is from about 0.9 pound-inches² to about 3.4 pound-inches².

Modulus of Elasticity can be determined for various materials fromstandard tables. It has been found that if a material is selected havinga Modulus of Elasticity in the range of about 4,000 psi to about 60,000psi and more preferably in the range of about 6,000 psi to about 40,000psi the attaining of a satisfactory value of (E)(I) is facilitated.Table 1 lists representative materials and their Moduli of Elasticity.

As can be appreciated, the proper selection of a fastener material inconjunction with the proper design of a fastener member is of paramountimportance for the comfort and functionality of the garment. If thefastener material is too inflexible it may cause discomfort and possibleinjury to the wearer. If the fastener material is too flexible, it maybe difficult to fasten, it may not remain fastened under normal usageand normal conditions and it may not maintain the shape of the garment,that is, it may allow the garment to roll or bunch up.

                  TABLE 1                                                         ______________________________________                                                             MODULUS OF                                               MATERIAL             ELASTICITY (psi)                                         ______________________________________                                        65% Dow 722          28,900-40,400                                            35% PP PROFAX* 7823  "                                                        50% DOW 722          71,000-89,000                                            35% PP PROFAX 7823   "                                                        50% EVA (ethylene vinyl acetate)                                                                   54,000-55,600                                            50% PP PROFAX 7823   "                                                        Injection Molded PP PROFAX 7823                                                                    46,000                                                   POLYURETHANE ESTANE** 58134                                                                         9,000                                                   POLYURETHANE ESTANE 58130                                                                          18,000                                                   POLYURETHANE ESTANE 58133                                                                          22,100                                                   POLYURETHANE ESTANE 58810                                                                          12,000                                                   ______________________________________                                         *PROFAX is a tradename of Hercules Co.                                        **ESTANE is a tradename of B. F. Goodrich                                

Referring again to FIG. 24, the fastener member 70 is comprisedgenerally of a flat portion 90, an aperture 92 and two configured clasps94, 96. The fastener member 70 as shown in FIG. 24 is obtained bycutting a section with a length "x" from the continuous roll of materialas described above. The cross section of the entire length "x" of thesection would be that as indicated by line 105. The aperture 92 is thenprovided which removes a portion of material from flat portion 90 and aportion of the clasp material which would be between clasps 94 and 96.

Referring now to FIG. 25 there is shown fastener member 74 (fastenermember 76 is the same). Fastener member 74 is made in a similar way tothat described above for fastener member 70. The fastener member 74 iscut from a continuous roll of material (not shown). This roll ofmaterial can be, and it is preferable, that it is the same roll ofmaterial that fastener member 70 is cut from. In this case the member 74is comprised generally of a flat portion or base 98, an aperture 100 andtwo clasps 102 and 104. The section is cut with a length "x'" which isslightly longer than the length "x" of fastener members 70, the reasonfor which will become apparent. In addition, as is shown in FIG. 25, thelength of aperture 100 is smaller than aperture 92 shown in FIG. 24. Theends of clasps 102 and 104 are sufficiently larger than the ends ofclasps 94 and 96 to allow ends of clasps 94 and 96 to interlock underclasps 102 and 104. The sides of clasps 102 and 104 may be bonded toflat portion 98 as indicated at 106. A preferable method of bonding isby autogenous bonding and autogenous bonds are indicated at 106.

Referring to FIGS. 24 and 25 and to the discussion relating to thevalues of EI above, the values of EI through the areas indicated by line105 (FIG. 24) and line 109 (FIG. 25) are selected to be in the range of0.5-3.5 pound-inches² and preferably in the range of 0.9-3.4pound-inches². The values of EI through the areas indicated by line 103(FIG. 24) and line 107 (FIG. 25) is selected to be in the range of 0.002to 0.010 pound-inches².

Referring to FIG. 26 there is shown individual clasps 102 and 94interlocked. The interrelationship of the clasps and the requiredrelationship of lengths "x" (FIG. 24) and "x'" (FIG. 25) is nowapparent. The fasteners members have a complementary cross section formating engagement and are releasably interlockable. The autogenous bonds106 bonding the edge of clasp 102 to flat area 98 serve a twofoldpurpose; one, to provide stability to the fasteners and two, to preventclasp 94 from sliding out from the side of clasp 102.

Turning now to a description of the materials used for the variouscomponents, it is desirable that the liquid permeable bodyside liner 42utilized in the disposable diaper of the present invention meet thefollowing criteria. One, the bodyside liner 42 should be dry, i.e., beand feel dry when the absorbent structure 22 is loaded with urine. Ameasure of this criterion is that the bodyside liner 42 feel dry to thetouch after a normal urine loading of the absorbent structure. Two, thez-direction (defined as the direction from the bodyside liner outward tothe outer cover) fluid penetration rate of bodyside liner 42 should behigh enough to allow urine to penetrate through to the absorbentcomposite at an infant's urination rate. Three, the feel, color andopacity are further criteria that are most preferably satisfied by awhite material, although other colors may be acceptable, with an opacitysufficient to mask the color of urine or feces within the absorbentcomposite. Four, bodyside liner 42 should be autogenously bondable toliquid impermeable barrier 44. Barrier 44 is preferably made frompolypropylene, however, other liquid impermeable materials can be used.

The bodyside liner is a soft, compressible material comprised ofsynthetic fibers such as polyester/polypropylene integrally bonded to atop liner at spaced apart sites to provide densified zones for fluidtransfer. Such a web is described in U.S. Pat. No. 4,397,644, issued toMattews et al. and assigned to the assignee of the present application,the disclosure of which is incorporated herein by reference and reliedupon. The top liner is a pattern bonded spunbonded web also of syntheticfibers such as polypropylene, polyester and the like. The combined basisweight of the bodyside liner should be in the range of about 30-100g/m². It should have a wetting finish throughout. The bottom layer ofthe bodyside liner is typically a carded web of polyester/polypropylenefiber containing up to 100% polyester fiber, preferably 25-50% polyesterstaple, containing sufficient surfactant finish to be wettable. Two-inchpolyester staple, Type T808, a hollow fiber, at 5.5 denier from E. I.duPont Co. with a wettable finish is preferred although other wettablepolyester staple fibers would work. Polypropylene Type T-123 fromHercules Inc. has a wettable finish with the 3-denier, 17/8 inch staplepreferred. The web is only bonded together through the spaced apartbonds which attach it to the liner, which are typically achieved throughthermal or ultrasonic bonding. The bottom layer may also be formed byother nonwoven processes such as spunbonding in which the filaments arespun and collected on a wire screen without bonding and then bonded tothe prebonded liner as described above. It should have a wetting finish,for example, as is achieved by treating with 0.2-0.5% TRITON X-102 fromRohm and Haas Co., or equivalent surfactant.

The outer cover 20 of the present invention is preferably made from aresiliently stretchable material having a stretchability of from about20 percent to about 200 percent. The term stretchability as used hereinis defined by the following relationship:

    stretchability=(final dimension-initial dimensional)/initial dimension)×100%

The outer cover 20 is also resilient, that is, the outer cover returnsessentially to its initial dimension when the stretching force isremoved.

One such resiliently stretchable material is disclosed in U.S. patentapplication, Ser. No. 760,698 in the name of Tony J. Wisneski andMichael T. Morman, assigned to the assignee of the present application,entitled "Polyolefin-containing Extrudable Compositions and Methods fortheir Formation Into Elastomeric Products", the disclosure of which isincorporated herein by reference and relied upon. That applicationprovides extrudable elastomeric compositions which, after extrusion,solidify to form elastomeric products such as, for example, fibrousnonwoven elastomeric webs. The extrudable elastomeric compositions areblends of (1) from at least about 10 percent, by weight, of an A-B-A'block copolymer, where "A" and "A'" are each a thermoplastic polymerendblock which includes a styrenic moiety such as a poly(vinyl arene)and where "B" is an elastomeric poly-(ethylene-butylene) midblock, with(2) from greater than 0 percent, by weight, to about 90 percent, byweight, of a polyolefin which, when blended with the A-B-A' blockcopolymer and subjected to appropriate elevated pressure and elevatedtemperature conditions, is extrudable, in blended form, with the A-B-A'block copolymer. The A-B-A' block copolymer serves to impart elastomericproperties to products formed from the extrudable composition and thepresence of the polyolefin in the blend serves to reduce the viscosityof the composition as compared to the viscosity of the neat, that is,pure, A-B-A' block copolymer and thus enhances the extrudability of thecomposition.

Preferably, the "A" and "A'" thermoplastic styrenic moiety containingendblocks of the block copolymer are selected from the group includingpolystyrene and polystyrene homologs such as, for example,poly-(alpha-methylstyrene). In some embodiments the "A" and "A'"thermoplastic styrenic moiety containing endblocks are identical.Preferably, the polyolefin is selected from the group including at leastone polymer selected from the group including polyethylene,polypropylene, polybutene, ethylene copolymers, propylene copolymers,butene copolymers or blends of two or more of these materials.

The blend usually includes from at least about 20 percent, by weight, toabout 95 percent, by weight, of the block copolymer and from at leastabout 5 percent, by weight, to about 80 percent, by weight, of thepolyolefin. For example, the blend may include from about 30 percent, byweight, to about 90 percent, by weight of the block copolymer and fromabout 10 percent, by weight, to about 70 percent, by weight, of thepolyolefin. Preferably, the blend includes from about 50 percent, byweight, to about 90 percent, by weight, the block copolymer and fromabout 10 percent, by weight, to about 50 percent, by weight, of thepolyolefin. For example, the blend may include from about 50 percent, byweight, to about 70 percent, by weight, of the block copolymer and fromabout 30 percent, by weight, to about 50 percent, by weight, of thepolyolefin. One blend includes about 60 percent, by weight, of thepolyolefin.

The extrudable composition is extruded or otherwise formed, such as, forexample, by molding, for example, injection molding, at an appropriate,that is effective, combination of elevated pressure and elevatedtemperature conditions. These conditions will vary depending on thepolyolefin utilized. For example, the extrudable composition should beextruded or otherwise formed at a temperature of at least about 125degrees Centigrade if polyethylene is utilized as the polyolefin in theblend or at least about 175 degrees Centigrade if polypropylene isutilized in the blend, for example, at a temperature of from at leastabout 290 degrees Centigrade to about 345 degrees Centigrade, morespecifically, at a temperature of from at least about 300 degreesCentigrade to about 335 degrees Centigrade, into elastomeric productssuch as, for example, elastomeric fibers, which may be collected as afibrous nonwoven elastomeric web.

Preferably the blends are extrudable within the above-definedtemperature ranges at elevated pressures within the die tip, (forexample, within the extrusion capillaries of a die tip having thirty(30) extrusion capillaries per lineal inch of die tip with each of thecapillaries having a diameter of 0.0145 inches and a length of 0.113inches) of no more than about 300 pounds per square inch, gage, forexample, from pressures of from about 20 pounds per square inch, gage,to about 250 pounds per square inch, gage. More specifically, the blendsare extrudable within the above-defined temperature ranges at pressuresof from about 50 pounds per square inch, gage, to about 250 pounds persquare inch, gage, for example, from about 125 pounds per square inch,gage, to about 225 pounds per square inch, gage. Higher elevatedpressures can be utilized with other die designs having a lower numberof capillaries per inch of die, but, generally speaking, lowerproduction rates result.

Importantly, it has been found that the extrudable compositions areextrudable at satisfactory throughput rates because the presence of thepolyolefin in the extrudable composition reduces the viscosity of theextrudable composition, as compared to the viscosity of the neat, thatis, pure, block copolymer, to satisfactory levels. This reducedviscosity proportionally reduces the die tip pressure if all otherparameters remain the same. For example, the viscosity of the extrudablecompositions will generally be less than about 500 poise when extrudedat the above-defined elevated temperature and elevated pressure ranges.Preferably, the viscosity of the extrudable composition is less thanabout 300 poise when extruded at the above-defined elevated temperaturesand elevated pressure ranges. For example, the viscosity of theextrudable composition may be from at least about 100 poise to about 200poise when extruded at the above-identified elevated temperature andelevated pressure conditions.

Because the polyolefin reduces the viscosity of the blend, as comparedto the viscosity of the block copolymer, the extrudable composition isextrudable within the above-identified elevated temperature and elevatedpressure ranges, through a die tip having, for example, thirtycapillaries per inch of die tip with the capillaries having a diameterof about 0.0145 inches and a length of about 0.113 inches at a rate offrom at least about 0.02 grams per capillary per minute to about 1.7 ormore grams per capillary per minute. For example, the extrudablecomposition may be extruded through the above-identified die tip havingcapillaries with a diameter of about 0.0145 inches and a length of about0.113 inches at the rate of from at least about 0.1 grams per capillaryper minute to about 1.25 grams per capillary per minute. Preferably, theextrudable composition is extrudable through the above-identified dietip having capillaries with a diameter of about 0.0145 inches and alength of about 0.113 inches at the rate of from at least about 0.3grams per capillary per minute to about 1.1 grams per capillary perminute.

The extrudable composition may be formed into fibrous nonwovenelastomeric webs preferably having microfibers with an average diameterof not greater than about 100 microns, and preferably having an averagebasis weight of not more than about 300 grams per square meter, forexample, an average basis weight of from about 5 grams per square meterto about 100 grams or more per square meter. More specifically, anaverage basis weight of from about 10 grams per square meter to about 75grams per square meter. For example, a fibrous nonwoven elastomeric webmay be formed by extruding the extrudable composition at an appropriate,that is, effective, combination of elevated temperature and elevatedpressure conditions. Preferably, the extrudable composition is extrudedat a temperature of from at least about 125 degrees Centigrade if thepolyolefin is polyethylene or at least about 175 degrees Centigrade ifthe polyolefin is polypropylene, for example, from about 290 degreesCentigrade to about 345 degrees Centigrade, more specifically from about300 degrees Centigrade to about 335 degrees Centigrade. Preferably, theextrudable composition is extruded within the above-identifiedtemperature ranges and pressures, within the die tip, (for example,within the extrusion capillaries of a die tip having thirty (30)extrusion capillaries per lineal inch of die tip with each of thecapillaries having a diameter of about 0.0145 inches and a length of0.113 inches) of no more than about 300 pounds per square inch, gage,for example, from about 20 pounds per square inch, gage, to about 250pounds per square inch, gage. More specifically, the extrudablecomposition is extruded at a pressure within the capillaries of theabove-identified die tip of from about 50 pounds per square inch, gage,to about 250 pounds per square inch, gage, for example, from about 125pounds per square inch, gage, to about 225 pounds per square inch, gage.

In the formation of elastomeric nonwoven webs, the extrudablecomposition is extruded, at the above-defined elevated temperature andelevated pressure conditions at a rate of from at least about 0.02 gramper capillary per minute to about 1.7 or more grams per capillary perminute, for example, from at least about 0.1 gram per capillary perminute to about 1.25 grams per capillary per minute, more specifically,from at least about 0.3 gram per capillary per minute to about 1.1 gramsper capillary per minute, through a die having a plurality of smalldiameter extrusion capillaries, as molten threads into a gas streamwhich attenuates the molten threads to provide a gas-borne stream ofmicrofibers which are then formed into the fibrous nonwoven elastomericweb upon their deposition on a collecting arrangement. The attenuatinggas stream is applied to the molten threads at a temperature of from atleast about 100 degrees Centigrade to about 400 degrees Centigrade, forexample, from about 200 degrees Centigrade to about 350 degreesCentigrade and at a pressure of from at least about 0.5 pound per squareinch, gage, to about 20 pounds per square inch, gage, for example, fromat least about 1 pound per square inch, gage, to about 10 pounds persquare inch, gage. The thread attenuating gas stream may be an inert,non-oxidizing, gas stream such as, for example, a stream of nitrogengas. In some embodiments the velocity and temperature of thethread-attenuating gas stream is adjusted so that the fibers arecollected as substantially continuous fibers having diameters of fromabout ten (10) microns to about sixty (60) microns, for example, from atleast about ten (10) microns to about forty (40) microns. The fibrousnonwoven elastomeric webs so formed will include elastomeric fiberscomposed of from at least about 10 percent, by weight, of the blockcopolymer and greater than 0 percent, by weight, and up to about 90percent, by weight, of the polyolefin. The fibers are usually composedfrom at least about 20 percent, by weight, to about 95 percent, byweight, of the block copolymer and from at least about 5 percent, byweight, to about 80 percent, by weight of the polyolefin. For example,the fibers may be composed from at least about 30 percent, by weight, toabout 90 percent, by weight, of the block copolymer and from least about10 percent, by weight to about 70 percent, by weight, of the polyolefin.Preferably, the fibers are composed from about 50 percent, by weight, toabout 90 percent, by weight, of the block copolymer and from at leastabout 10 percent, by weight, to about 50 percent, by weight, thepolyolefin. For example, tne fibers may be composed from at least about50 percent, by weight, to about 70 percent, by weight, of the blockcopolymer and from at least about 30 percent, by weight, to about 50percent, by weight, of the polyolefin.

Another such resiliently stretchable material is disclosed in U.S.patent application, Ser. No. 760,437 in the name of Jack D. Taylor andMichael J. Vander Wielen and assigned to the assignee of the presentapplication, entitled "Composite Elastomeric Material and Process forMaking the Same", the disclosure of which is incorporated herein byreference and relied upon. That application provides a method ofproducing a composite elastic material comprising at least onegatherable web bonded to at least one elastic web, the method comprising(a) tensioning an elastic web (which may comprise a fibrous web such asa nonwoven web of elastomeric fibers, for example, meltblown elastomericfibers) to elongate it; (b) bonding the elongated elastic web to atleast one gatherable web under conditions which soften at least portionsof the elastic web to form a bonded composite web; and (c) relaxing thecomposite web immediately after the bonding step whereby the gatherableweb is gathered to form the composite elastic material. The fibrouselastic web can also be maintained in a stretched condition during thebonding, at an elongation of at least about 25 percent, preferably about25 percent to over 500 percent, for example, about 25 percent to 550percent elongation during the bonding. The method also includes bondingthe elongated elastic web to the gatherable web by overlaying theelastic and gatherable webs and applying heat and pressure to theoverlaid webs, for example, by heating bonding sites on the elastic webto a temperature of from at least about 65 degrees Centigrade to about120 degrees Centigrade, preferably from at least about 70 degreesCentigrade to about 90 degrees Centigrade.

That application also provides an elastic composite material comprisingan elastic web bonded to at least one gatherable web which is extensibleand contractible with the elastic web upon stretching and relaxing ofthe composite material, the elastic composite material being made by amethod as described above. Also provided is an elastic web that isbonded to the gatherable web at a plurality of spaced-apart locations ina repeating pattern and the gatherable web is gathered between thebonded locations. The elastic web may comprise a nonwoven web ofelastomeric fibers, preferably elastomeric microfibers, such as, forexample, an elastomeric nonwoven web of meltblown elastomeric fibers oran elastomeric film.

The elastic composite material may include one or more of the followingin any combination: the elastomeric fibers, preferably meltblownelastomeric fibers, may be formed from material selected from the groupincluding (i) A-B-A' block copolymers wherein "A" and "A'" may be thesame or different endblocks and each is a thermoplastic polymer endblockor segment which contains a styrenic moiety such as polystyrene orpolystyrene homologs, and "B" is an elastomeric polymer midblock orsegment, for example, a midblock selected from the group includingpoly(ethylene-butylene), polyisoprene and polybutadiene, withpoly(ethylene-butylene) being preferred and (ii) blends of one or morepolyolefins with the A-B-A' block copolymers of (i) where "B" is apoly(ethylene-butylene) midblock; each of the "A" and "A'" endblocks maybe selected from the group consisting of polystyrene and polystyrenehomologs, for example, poly(alpha methylstyrene), and where theelastomeric fibers are formed from a blend of one or more polyolefinswith an A-B-A' block copolymer where "B" is a poly(ethylene-butylene)midblock, the polyolefin is selected from one or more of polyethylene,polypropylene, polybutene, ethylene copolymers, propylene copolymers andbutene copolymers; the elastomeric film and the elastomeric fibers whichform the elastomeric nonwoven web, for example, the meltblownmicrofibers, are composed of at least 10 percent, for example at least20 percent, more specifically at least 30 percent, for example, fromabout 10 percent to 90 percent, by weight, of the aforesaid A-B-A' blockcopolymers and greater than 0 percent, by weight, for example, fromabout 90 percent to about 10 percent, by weight, of the polyolefin; theelastic web, for example, a fibrous elastic web, is bonded to thegatherable web at a plurality of spaced-apart locations in a repeatingpattern and the gatherable web is gathered between the bonded locations;the elastic web preferably has a low basis weight of from about 5 toabout 300, preferably from about 5 to about 200, grams per square meter,for example, from about 5 to about 100 grams per square meter, althoughits basis weight can be much higher; the gatherable web is a nonwoven,non-elastic material, preferably one composed of fibers formed frommaterials selected from the group including polyester fibers, forexample, poly(ethylene terephthalate) fibers, polyolefin fibers,polyamide fibers, for example, nylon fibers, cellulosic fibers, forexample, cotton fibers, and mixtures thereof. Alternatively, thegatherable web may be any suitable woven fabric. In a particular aspect,the composition of the A-B-A' polymer used is such that the sum of themolecular weight of "A" with the molecular weight of "A'" is from about14 to 31 percent (from about 14 to 29 percent when "B" ispoly(ethylene-butylene)) of the molecular weight of the A-B-A' blockcopolymer.

A further such resiliently stretchable material is disclosed in U.S.patent application, Ser. No. 760,449, in the name of Michael J. Morman,and assigned to the assignee of the present invention, entitled"Composite Nonwoven Elastic Web", the disclosure of which isincorporated herein by reference. That application is directed to aprocess for producing a composite nonwoven elastic web which is composedof a nonwoven elastic web that is joined to a fibrous nonwoven gatheredweb. In particular, the process disclosed therein produces a compositenonwoven elastic web which, in its relaxed, nonstretched state, iscomposed of a gathered nonwoven fibrous web that is joined to a nonwovenelastic web with the nonwoven elastic web having been relaxed from astretched, biased length to a relaxed, unbiased, nonstretched length soas to gather the fibrous nonwoven gathered web. An important feature ofthe process disclosed therein is that the fibrous nonwoven gatherableweb is formed directly onto a surface of the nonwoven elastic web whilethe nonwoven elastic web is maintained in a stretched, biased andelongated condition. The nonwoven elastic web may be formed by, forexample, a meltblowing process or any other process for forming anonwoven elastic web. For example, the nonwoven elastic web could be anapertured web of an elastic film as opposed to a meltblown fibrousnonwoven elastic web. The formed nonwoven elastic web has a normalrelaxed, nonstretched, nonbiased length. Thereafter, the nonwovenelastic web is elongated by being stretched to a stretched, biasedlength. In a subsequent step of the process a fibrous nonwovengatherable web may be formed, for example, by either a meltblowing orspinbonding process or any other process for forming a fibrous nonwovengatherable web, directly upon a surface of the nonwoven elastic webwhile the nonwoven elastic web is maintained at its elongated, stretchedand biased length. During formation of the fibrous nonwoven gatherableweb the nonwoven elastic web is maintained at a stretched length whichis at least about 125 percent, that is, at least about one and onequarter of the relaxed, unbiased length of the nonwoven elastic web. Forexample, the stretched, biased length of the nonwoven elastic web may bemaintained in the range of from at least about 125 percent of therelaxed, unbiased length of the nonwoven elastic web to about 700 ormore percent of the relaxed, unbiased length of the nonwoven elasticweb. The fibrous nonwoven gatherable web is joined to the nonwovenelastic web while the nonwoven elastic web is maintained at itselongated stretched, biased length. This results in the formation of acomposite nonwoven elastic web which includes the nonwoven elastic webwhich is joined to the fibrous nonwoven gatherable web. Because thefibrous nonwoven gatherable web is formed directly onto the surface ofthe nonwoven elastic web while the nonwoven elastic web is beingmaintained at its stretched, biased length, the nonwoven elastic web is,at this stage in the process, elongated, stretched and biased and thefibrous nonwoven gatherable web is in an ungathered but gatherablecondition. In one aspect, the joining of the fibrous nonwoven gatherableweb to the nonwoven elastic web is achieved by heat-bonding to fuse thetwo webs to each other. The heat-bonding may be carried out within thetemperature range of from about 50 degrees centigrade below the melttemperature of at least one of the materials utilized to form at leastone of the two webs to about the melt temperature of at least one of thematerials utilized to form at least one of the two webs. At highthrough-put rates the heat-bonding can be carried out above the melttemperature of one or more of the materials utilized to form the webs.The heat-bonding may also be carried out under appropriate conventionalpressurized conditions. If desired, conventional sonic bondingtechniques may be substituted for the heat-bonding steps.

The application also discloses another embodiment whereby the joining ofthe fibrous nonwoven gatherable web to the stretched nonwoven elasticweb is achieved solely by the entanglement of the individual fibers ofthe fibrous nonwoven gatherable web with the nonwoven elastic web duringformation of the fibrous gatherable web on the surface of the elasticweb. If the nonwoven elastic web is a fibrous nonwoven elastic webformed by, for example, meltblowing, entanglement of the individualfibers of the fibrous nonwoven gatherable web with the fibrous nonwovenelastic web is achieved by entanglement of the individual fibers of thefibrous gatherable web with the individual fibers of the fibrous elasticweb. If the nonwoven elastic web is an apertured film, joining of thefibrous nonwoven web with the film is achieved by entanglement of theindividual fibers of the fibrous gatherable web within the apertures ofthe film. The joining of the two webs to each other can also be achievedby forming the nonwoven elastic web out of a tacky elastic material, aprocess that will be discussed hereinafter. In addition, the joining ofthe two webs to each other may be further enhanced by applying pressureto the two webs after the gatherable web has been formed on the surfaceof the elastic web. Further improvement in the joining of the two webscan be obtained by applying an adhesive material to the upper surface ofthe nonwoven elastic web prior to formation of the fibrous nonwovengatherable web thereon.

After joining of the two webs to each other has been achieved to form acomposite elastic web, the biasing force is removed from the compositenonwoven elastic web and the composite elastic web is allowed to relaxto its normal relaxed, unbiased length. Because the fibrous nonwovengatherable web is joined to the nonwoven elastic web while the nonwovenelastic web is stretched, relaxation of the composite nonwoven elasticweb results in the gatherable web being carried with the contractingnonwoven elastic web and thus being gathered. After gathering of thefibrous nonwoven gatherable web has occurred by reducing the biasingforce on the composite nonwoven elastic web, the composite nonwovenelastic web may be rolled up in rolls for storage and shipment ofdirected to a manufacturing process for the production of products suchas the disposable garments taught by the present application.

As indicated above, the process disclosed in U.S. patent applicationSer. No. 760,449 can be enhanced by the utilization of a tacky fibrousnonwoven elastic web which can be formed by, for example, meltblowingmicrofibers of a tacky elastic material such as, for example, an A-B-A'block copolymer or blends of such A-B-A' block copolymers withpoly(alpha-methylstyrene) where "A" and "A'" are each thermoplasticpolystyrene or polystyrene homolog endblocks and "B" is an elasticpolyisoprene midblock. In some embodiments "A" may be the samethermoplastic polystyrene or polystyrene homolog endblock as "A'". Thetacky fibrous nonwoven elastic web is then elongated by being stretchedto an elongated, stretched length and a fibrous nonwoven gatherable webis formed, for example, by meltblowing or spinbonding the fibrousnonwoven gatherable web, directly upon a surface of the tacky fibrousnonwoven elastic web while maintaining the fibrous nonwoven elastic webat its stretched length. As a result of the fact that the fibrousnonwoven elastic web is tacky, the fibrous nonwoven gatherable web issimultaneously formed upon and adhesively joined to the surface of thetacky fibrous nonwoven elastic web. This results in the formation of acomposite nonwoven elastic web having an ungathered fibrous gatherableweb adhesively joined to the tacky fibrous nonwoven elastic web with thejoining of the two webs to each other being achieved by the adhesivejoining which occurs during formation of the fibrous nonwoven gatherableweb on the surface of the fibrous nonwoven elastic web. The adhesivejoining of the two webs to each other may be increased upon applicationof pressure to the composite nonwoven elastic web by passing thecomposite nonwoven elastic web through the nip between rollers, whichmay be unheated, after the composite web has been formed but before thefibrous tacky nonwoven elastic web is allowed to relax. The adhesivejoining may be further enhanced by application of an adhesive materialto the surface of the tacky fibrous nonwoven elastic web prior toformation of the gatherable web thereon. The composite nonwoven elasticweb is then allowed to relax to its normal relaxed, unbiased length.Because the fibrous nonwoven gatherable web is joined to the tackyfibrous nonwoven elastic web while the tacky fibrous nonwoven elasticweb is in a stretched condition, relaxation of the composite nonwovenelastic web and thus the tacky fibrous nonwoven elastic web results inthe gatherable web being carried with the contracting fibrous nonwovenelastic web and thus being gathered. After gathering of the fibrousnonwoven gatherable web has occurred the composite nonwoven elastic webmay be rolled up in rolls for storage or directly applied to amanufacturing process for the production of disposable garments such asthe disposable garments taught by the present application.

The U.S. patent application, Ser. No. 760,449 is also directed to acomposite nonwoven elastic web composed of a nonwoven elastic web thatis joined to a gatherable fibrous nonwoven web which has been gatheredand with the composite web having been formed by any of the embodimentsof the process disclosed above. In particular, the composite nonwovenelastic web, in its relaxed, nonstretched state, is composed of anonwoven elastic web that is joined to a fibrous nonwoven gathered webwhich has been gathered as a result of the nonwoven elastic web havingbeen relaxed from an elongated stretched, biased length to a relaxed,unbiased nonstretched length. Exemplary elastomeric materials for use information of the fibrous nonwoven elastic web include polyesterelastomeric materials, polyurethane elastomeric materials, and polyamideelastomeric materials. Other elastomeric materials for use in formationof the fibrous nonwoven elastic web include (a) A-B-A' block copolymers,where "A" and "A'" are each a thermoplastic polymer endblock whichincludes a styrenic moiety and where "A" may be the same thermoplasticpolymer endblock as "A'", such as a poly(vinyl arene), and where "B" isan elastomeric polymer midblock such as a conjugated diene or a loweralkene or (b) blends of one or more polyolefins or poly(alpha-methylstyrene) with A-B-A' block copolymers, where "A" and "A'" are each athermoplastic polymer endblock which includes a styrenic moiety, where"A" may be the same thermoplastic polymer endblock as "A'", such as apoly(vinyl arene) and where "B" is an elastomeric polymer midblock suchas a conjugated diene or a lower alkene. The "A" and "A'" endblocks maybe selected from the group including polystyrene and polystyrenehomologs and the "B" midblock may be selected from the group includingpolyisoprene, polybutadiene or poly(ethylene-butylene). If "A" and "A'"are selected from the group including polystyrene or polystyrenehomologs and "B" is poly(ethylene-butylene), materials which may beblended with these block copolymers are polymers, including copolymersof ethylene, propylene, butene, other lower alkenes or one or more ofthese materials. If "A" and "A'" are selected from the group includingpolystyrene or polystyrene homologs and "B" is a polyisoprene midblock,a material for blending with this type of block copolymer ispoly(alpha-methylstyrene).

It is to be clearly understood that the description of methods formaking a material suitable for outer cover 20 and the description ofmaterials suitable for use as outer cover 20 is exemplary only and isnot meant to be limiting. Other resiliently stretchable materials couldbe used without departing from the spirit and scope of the presentinvention.

Various materials are contemplated for use as the absorbent compositeincluding fibrous materials, foams, particulates, etc. In general, themost economical liquid absorbent material for use in disposable diapershas been an absorbent fiber. The absorbent fiber most commonly used iscellulosic fiber such as comminuted wood pulp, commonly known in the artas "pulp fluff ," or simply "fluff." Absorbent composites made fromthese fibers generally have a low density and a high capacity forabsorbing fluids, but it has been found that their wicking capability isrelatively poor. One prior art approach to solve the relatively poorwicking capability is taught in U.S. Pat. No. 4,213,459, issued to Sigl,assigned to the assignee of the present invention. U.S. Pat. No.4,213,459 teaches a method wherein the pore size of the absorbentcomposite are decreased such that the improved capillary action of thepores overcomes the force of gravity to cause the waste liquid to moveupwardly to other parts of the absorbent composite. Another approach tosolve the problem of poor wicking capability is to provide an absorbentcomposite with at least two layers of cellulosic fibers of differentdensities or different average pore sizes. The absorbent composite maycomprise a first, lower density layer of cellulosic fibers such as fluffwhich lies directly beneath bodyside liner 42 with a second, higherdensity layer of fluff beneath the first layer. Predominantly softwoodpulp fluff could be used for each of the above-described layers.Alternatively, a layer of predominantly softwood fluff can be used forthe first layer and a layer of preponderantly hardwood fluff could beused for the second layer, in which case it is the average pore size andnot necessarily the density that varies between the first and secondlayers. For the purposes of this disclosure, "predominantly" is intendedto mean at least about 80% while "preponderantly" is intended to mean atleast about 50%. Another alternative is to vary the pore size withoutnecessarily varying the density. This can be done because hardwood fluffhas a smaller pore size than softwood fluff and as a result, if hardwoodfluff fibers are used as a replacement for the higher density softwoodfluff fibers, two different pore size distributions will be obtained,even if the density of each layer is the same. Thus, for example, a twocomponent fluff sandwich comprising a coarse pore structure in the firstlayer obtained from a predominantly softwood fluff pulp and a fine porestructure in the second layer comprised of a preponderantly hardwoodfluff, densified throughout to one density can be used.

A second aspect relating to the absorbent composite relates to includinga portion of a hydrogel as part of the absorbent composite. The term"hydrogel" as used herein refers to one or more hydrocolloid materialscapable of absorbing many times their own weight of water or aqueousfluid. These materials are generally prepared by polymerizing one ormore monomers which, if homopolymerized by conventional methods, wouldform water soluble polymers. To render them water-insoluble and suitablefor the present invention, these polymers or mixture of polymers aretypically reacted, frequently with a crosslinking agent, to formcrosslinked polymers, thereby introducing a limited water-insolubilitywhile retaining susceptibility to swelling in water and water-containingfluids. Pseudocrosslinking may also be achieved by chain entanglement ofhigh-molecular weight polymers, thus effecting water insolubility.Typically, these hydrocolloids are salts of polyacrylic acid andvariations thereof, such as methacrylic acid. Commercially they areavailable under such trademarks as Water Lock from Grain ProcessingCompany; Arasorb 720 from Arakawa Chemical, Inc. (U.S.A.); andAqualic-CA from Nippon Shakubai/Japanese Catalytic Chemical Company.Alternative hydrogels may also include hydrophilic polymers grafted ontostarch or cellulose backbones and crosslinked carboxylated celluloses.

The hydrogel may be sandwiched between a first higher density layer anda second higher density layer or between a low density layer and a highdensity layer. The hydrogel may be also disposed adjacent to a higherdensity layer which is in turn covered with a lower density layer. Inaddition to the absorbent composite being structured in layers, thehydrogel material may be disposed within the absorbent composite as apowder, fiber, etc., forming a mixture. The absorbent composite, in thatcase, may be provided with uniform densification of all layers to about0.1 g/cc., or in the range of about 0.1 g/cc. to about 0.35 g/cc.

The term "density" as used herein refers to the density of the compositestructure of the lower density layer or the higher density layer, andnot the actual fiber density. (The actual fiber density is about 1.5g/cc.) The density of the lower density layer should be in the range ofabout 0.03 to about 0.14 g/cc., with the preferred range at about 0.07to about 0.11 g/cc. The higher density layer should have a density inthe range of about 0.14 to about 0.35 g/cc., and preferably in the rangeof about 0.16 to about 0.3 g/cc. for providing the desired capillaritywithout excessive stiffness. The density for these preferred ranges is adensity measured under a load of 0.2 psi.

Comminuted wood pulp (fluff) is preferred as an absorbent fiber, butother cellulose fibers such as cotton linters can be used. The preferredfluff is southern pine kraft wood pulp (i.e., made according to thesulfate process commonly known in the art) which has been bleached, suchas can be purchased from International Paper Company. A suitablehardwood fluff pulp is Southern Hardwood Kraft obtainable fromWeyerhaueser Company as "New Bern 309."

Alternate embodiments may be utilized without departing from the spiritof the invention. For example, the densified fluff layer could also beused with other absorbents such as coformed (meltblown polymer fiberscombined with wood pulp and/or stable fibers) webs, carded webs,air-formed (staple wood pulp blends) webs, and the like, at a lowerdensity.

According to a further aspect of the present invention, the absorbentcomposite may comprise a mixture of a hydrogel material with 2-98% byweight of a filler material. The "filler materials" may include a widevariety of materials in powder, fiber, or particulate form such as anabsorbent fiber wherein the absorbent fiber may be a cellulosic fiber(as described above), a hydrophilic material or a hydrophobic material.The filler materials may be treated with a surfactant to improve surfacewetability. Examples include polyolefins such as polyethylene,polypropylene, and polystyrene, as well as natural, slightly absorbentclays, micas or vegetable (for example, corn cob) debris as well asblends of these materials. See U.S Pat. No. 4,381,782 to Mazurak et al.,the disclosure of which is incorporated herein by reference and reliedupon.

Surfactants which may be utilized in accordance with the inventioninclude ionic and nonionic materials such as Aerosol O. T. (AmericanCyanamid), Teepol 610 (Particle Data Laboratories, Ltd.), Neodol-27(Shell Chemical Company), Duomeen-361 (Armour Industrial ChemicalCompany), and Triton X-102 (Rohm and Haas Co.).

The filler material is first uniformly wetted with up to about 20% byweight of surfactant solution containing surfactant in the range of fromabout 0.5% to 2.5% by weight. The hydrogel powder is then added and theadmixture thoroughly blended to provide an intimate mixture andintegration throughout of the components. The hydrogel particles willswell slightly and adhere to the filler material. After drying, theadmixture is preferably subjected to slight mechanical action destroyinglumps. In use the filler material acts to rapidly wick liquid throughoutthe mixture and substantially eliminate the tendency to form gel blocks.While it is not desired to limit the invention to any particular theory,it is believed that the surfactant liquid slightly swells the dryhydrogel making it sticky and allowing it to adhere to filler particles.For this reason it is preferred that the filler be damp, including up to10% by weight of water prior to mixing with surfactant solution.

The amounts of filler material are in the range of 2-98% by weight withthe preferred amount being in the range of 5% to 95% and, even morepreferably, 25% to 75%, based on the weight of hydrogel material. Thesurfactant is preferably added to filler material in an amount of about0.05% to 0.5% and, more preferably, 0.1% to 0.2% by weight based on theamount of nonabsorbent filler. The filler material is of relativelylarge average particle diameter in the range of from 1-10,000,preferably 1-1,000, and, most preferred 10-100 times the averagehydrogel particle diameter.

Thus, while the invention has now been described with reference toseveral preferred embodiments and illustrated with regard to a range ofoptional features, those skilled in the art will appreciate that varioussubstitutions, omissions, modifications, and changes may be made withoutdeparting from the spirit hereof. Accordingly, it is intended that theforegoing description be deemed merely exemplary of the preferred scopeof the present invention and not to be deemed a limitation thereof.

What is claimed is:
 1. A fixed point fastener system for a disposableabsorbent garment of the type having leg and waist portions, saidfastener system comprising:an outer cover; an absorbent structureincluding a liquid impervious barrier means, a liquid pervious body sidelinear means and an absorbent component therebetween; said fixed pointfastener system including first and second pairs of like fastenermembers respectively attached to fixed fastening locations on said outercover and having complementary cross sections for maintaining releasablyinterlocking mating engagement of each of said first pair of fastenermembers with each of said second pair of fastener members withoutpenetration thereof into said outer cover, each of said fastener membershaving an essentially flat flexible base extending between the waist andleg portions with a pair of clasps disposed thereon, said pair of claspsbeing separated by an apertured first portion of said base, for allowingflexion of said base thereat, said fastener members being sufficientlyflexible to prevent skin irritation of the wearer and sufficientlyinflexible to prevent unwanted unfastening thereof.
 2. The fastenersystem of claim 1, wherein a value EI is a measure of the flexibilityand inflexibility of said fastener members and is calculated from theformula EI=L³ M/48 and wherein a first value of EI is measured through across section of each of said fastener members including said clasps andis preferably in the range from 0.5 pound-inches² to 3.5 pound-inches².3. The fastener system of claim 2, wherein said first value EI is mostpreferably in the range from 0.9 pound-inches² to 3.4 pound-inches². 4.The fastener system of claim 3, wherein a second value of EI is measuredthrough a cross section of said fastener member including said firstportion and is preferably in the range from 0.002 pound-inches² to 0.010pound-inches².
 5. The fastener system of claim 4, further comprisingprevention means for preventing said first pair of fastener members fromsliding laterally from engagement with said second pair of fastenermembers.
 6. The fastener system of claim 5, wherein said preventionmeans comprise bonds between at least one edge of each of said pair ofclasps and said base.
 7. The fastener system of claims 1 or 6 whereinsaid outer cover is formed from an extrudable material comprising anA-B-A' block copolymer and a polyolefin that is resiliently stretchablein the range of from about 20 percent to about 200 percent.
 8. Thefastener system of claim 7 wherein said fastener members are preferablymade from a material with a Modulus of Elasticity from about 4,000pounds per square inch to about 60,000 pounds per square inch.
 9. Thefastener system of claim 8 wherein said fastener members are mostpreferably made from a material with a Modulus of Elasticity from about6,000 pounds per square inch to about 40,000 pounds per square inch. 10.The fastener system of claim 9 wherein said bases on one of said firstor second pair of fasteners each include an outer edge having a tabextending outwardly away therefrom for aiding in fastening andunfastening said fastener system.
 11. A fixed point fastener system fora disposable absorbent garment of the type having leg and waistportions, said fastener system comprising:a nonwoven outer cover formedfrom an extrudable material comprising polyolefin and an A-B-A' blockcopolymer that is resiliently stretchable in the range from about 20% toabout 200%; an absorbent structure including a liquid impervious outerliner means, a liquid pervious body side liner means and an absorbentcomponent therebetween; said fixed point fastener system acting inconjunction with said resilient outer cover, including first and secondpairs of like fastener members respectively attached to fixed fasteninglocations on said outer cover and having complementary cross sectionsfor maintaining releasably interlocking mating engagement of each ofsaid first pair of fastener members with each of said second pair offastener members without penetration thereof into said outer cover, saidfastener members being sufficiently flexible to prevent skin irritationof the wearer and sufficiently inflexible to prevent unwantedunfastening of said fastener members.
 12. The fastener system of claim11 wherein each of said fastener members comprises an essentially flatflexible base extending between the waist and leg portions and having apair of clasps disposed thereon, said pair of clasps being separated bya first portion of said base, for allowing flexion of said base at saidfirst portion.
 13. The fastener system of claim 12, wherein said firstportion of said base has an aperture therein.
 14. The fastener system ofclaim 11 wherein said fastener member are preferably made from amaterial with a Modulus of Elasticity from about 4,000 pounds per squareinch to about 60,000 pounds per square inch.
 15. The invention of claim1 wherein said outer cover comprises an elastomeric nonwoven fabricresiliently stretchable at least 20%.
 16. The invention of claim 1wherein said outer cover is resiliently stretchable in the range fromabout 20% to about 200%.